This patch adding option to control weight of haproxy
backends per service via host variable.

Example:

[control]
server1 haproxy_nova_api_weight=10
server2 haproxy_nova_api_weight=2 haproxy_keystone_internal_weight=10
server3 haproxy_keystone_admin_weight=50

If weight is not defined, everything is working as before.

Change-Id: Ie8cc228198651c57f8ffe3eb060875e45d1f0700

Haproxy was renamed in [1].

[1] https://review.opendev.org/c/openstack/kolla-ansible/+/770618

Change-Id: Ib2d7f0774fede570a8c4c315d83afd420c31da0b

This patch is adding configuration option to
manipulate with kernel option sysctl_net_ipv4_tcp_retries2.

More informations about kernel option in [1][2]
and RedHat suggestion [3] to set for DBs and HA.

[1]: https://pracucci.com/linux-tcp-rto-min-max-and-tcp-retries2.html
[2]: https://blog.cloudflare.com/when-tcp-sockets-refuse-to-die/
[3]: https://access.redhat.com/solutions/726753

Closes-Bug: #1917068
Change-Id: Ia0decbbfa4e33b1889b635f8bb1c9094567a2ce6